The invention is based on a solenoid valve which is provided for insertion into a receiving bore in a hydraulic block of a slip-controlled hydraulic brake system of a vehicle. In particular, the solenoid valve is provided as a wheel brake pressure reduction valve that is connected to a wheel brake cylinder and is disposed between the wheel brake cylinder and a suction side of a return feed pump.
A solenoid valve of this kind has been disclosed by DE 197 00 495 A1. In this solenoid valve, the tubular valve dome is equipped at an open end with a hollow conical or annular step-shaped enlarged section with which it engages around a fittingly embodied collar of the valve support. The valve dome and the valve support are fastened in the receiving bore of the hydraulic block by means of a first caulk, which is formed out of the material of the hydraulic block and engages the enlarged section of the valve dome. The valve dome also has an annular component slid onto the valve dome and supported against the first caulk, which is fastened in the receiving bore at a mouth end by means of a second caulking of the hydraulic block. The sleeve-shaped valve support is of one piece with a valve seat which is engaged by an armature-actuated valve closing body and is provided with a cup point at the bottom which digs into the material of the hydraulic block at the bottom of the receiving bore and divides a valve inlet extending radially in the hydraulic block and in the valve support from an axially extending valve outlet of the hydraulic block. The caulks and the cup point seal eliminate the need for elastomer sealing elements. But the assembly of the solenoid valve is relatively costly due to the successively produced caulks.
U.S. Pat. No. 4,610,428 has disclosed a solenoid valve with a valve dome which has an annular step-shaped enlarged section at an open end. This enlarged section rests in a complementary step of a shaped sheet metal part serving as a valve support. With the interposition of a sealing ring, a collar of a valve seat part disposed in the valve dome engages in the annular step-shaped enlarged section of the valve dome. The valve support is not subjected to any stress by a fluid and therefore does not fulfill any sealing function. It merely serves to fasten the solenoid valve to the outside of a valve block.
A solenoid valve disclosed by U.S. Pat. No. 5,423,602 has an undercut-free valve support into which a valve seat part is press-fitted. A projection formed onto the valve support remote from the valve seat part is encompassed in a fluid-tight fashion by the open end of a valve dome.
Furthermore, DE 40 30 971 A1 has disclosed a solenoid valve with a valve support, which has a projection that is encompassed by the open end of a valve dome and is welded to this valve dome in a fluid-tight fashion.
A solenoid valve disclosed by EP 0 675 030 A2 has a hollow cylindrical valve dome into which a cylindrical pole is inserted and in which an armature is contained in an axially movable fashion. A coil is placed onto the valve dome in order to actuate the solenoid valve. The known solenoid valve is closed when without current; its armature can lift a valve closing body up from a valve seat counter to the force of a valve closing spring. If the known solenoid valve were embodied so as to be open when without current, it would be possible for the armature to press the valve closing body against the valve seat counter to the force of a valve opening spring. The valve seat is embodied on a valve seat part, which is disposed flush at an open end of the valve dome.
In order to fasten the solenoid valve in the receiving bore of the hydraulic block, a circular ring-shaped valve support is provided in which the valve dome engages with its open end. The solenoid valve is fastened in the receiving bore of the hydraulic block through the use of a fastening plate which has a hole let into the fastening plate with the diameter of the valve dome and the valve dome is inserted through this hole. The fastening plate is clamped between the valve support and the coil. The fastening plate is affixed to the valve block and secures the solenoid valve to the valve support in the receiving bore.
In order to produce a seal between the valve support and the valve dome, a sealing ring is inserted into a circumferential inner groove in the circular ring-shaped valve support. The seal between the valve support and a wall of the receiving bore is produced by a sealing ring which is inserted into an annular step of the valve support. A sealing ring is also provided to produce a seal between the valve seat part and the receiving bore, and is inserted into a groove running around the circumference of the valve seat part or a valve seat part holder into which the valve seat part is press-fitted. A valve inlet is produced by means of radial bores which are let into the valve support and valve seat part holder and which connect to an end of the valve seat part oriented toward the armature.
The known solenoid valve has the disadvantage that the known solenoid valve is costly to manufacture since both the valve support and the valve seat part holderxe2x80x94with their grooves and steps for the sealing rings and with the lateral bores for the valve inletxe2x80x94must be expensively produced in a material-cutting fashion and that the fastening plate, which is clamped between the valve support and the coil and must be affixed to the hydraulic block, makes assembly expensive.
The solenoid valve according to the invention, has an advantage that the attachment of the valve dome to the valve support and also the attachment of the valve seat part to the valve dome are achieved in a positively engaging and/or frictionally engaging manner by means of a non-cutting shaping process such as flanging or caulking of the valve support. This kind of connection between the valve dome, the valve seat part, and the valve support also simultaneously produces the seal between these parts without requiring a sealing element. This saves not only the cost of the sealing element, but also the assembly cost for affixing the sealing element. Another advantage of the solenoid valve according to the invention is the possibility of embodying the solenoid valve as compact in the axial direction by virtue of the connection and sealing of the valve dome, the valve seat part, and the valve support.
Advantageous embodiments and modifications of the invention disclosed in herein are the subject of the invention set forth hereinafter
In an embodiment of the invention a valve inlet and valve outlet are produced through the open end of the valve dome, for example in an axial or axially parallel fashion. This eliminates the need for the production of a lateral hole in the valve dome, the valve support, the valve seat part, or the valve seat part holder, which constitutes a considerable simplification in the manufacture of the solenoid valve since it is difficult and therefore costly to produce a lateral hole of this kind.